Novel capsule dipping apparatus

ABSTRACT

An improved apparatus is provided for producing pharmaceutical capsules by the dipping technique. For the conventional bottom feed dipping pan the improvement comprises open-end tunnel means below the pan whereby overflow dipping solution from opposite sides of the dipping pan is selectively channeled to opposite ends of the pan reservoir for lengthwise and depthwise recycling to the dipping pan by way of the tunnel.

Unite States Patent 11 1 Weyers 1 1 Sept. 4, 1973 [S4] NOVEL CAPSULE DIPPING APPARATUS 1,787,777 1/1931 Colton 425/96 r 2,353,256 7/1944 Ma Wald, .lr. 425/270 X [75] Inventor Relgerslaam 2,575,789 11/1951 Bog in 425/272 x Belgium 2,975,477 3/1961 Hostetler 425/270 [73] Assignee: Parke, Davis & Company, Detroit, 7

i YJTK tQit/flzRWfiL- $99 91 [22] Filed: Nov. 30, 1972 Attorney-Robert R. Adams, David B. Ehrlinger et 21 Appl. No.: 310,829

Related US. Application Data [57] ABSTRACT [63] Continuation of Ser. No. 159,838, July 6, 1971, Y

abandoned' An improved apparatus is provided for producing pharmaceutical capsules by the dipping technique. For the 52 us. 01. 425/270, 425/273 conventional bottom feed dipping pan the improve [51] Elli. Cl. B29! 13/00 ment comprises 0pen end tunnel means below the pan [58] held of Search 425/269, 270, 272, whereby overflow dipping solution from Opposite sides 425/273 of the dipping pan is selectively'channeled to opposite ends of the pan reservoir for lengthwise and depthwise [56] References C'ted recycling to the dipping pan by way of the tunnel, UNITED STATES PATENTS v 943,608 12/1909 Scott 425/273 6 Claims, 6 Drawing Figures I 41 27 l6 18 b N v 9 9 F 2 2 L 4 j A 22 g PATENTED 41975 SHEET 1 BF 2 2; INVENTOR.

HUGO JOZEF WEYERS Mn. m,

ATTY.

PAIENTEDSEP" 41m 3.756.759

SHEET 2 OF 2 HUGO JOZEF WEYERS W157. ATTY.

1 NOVEL CAPSULE DIPPING APPARATUS RELATED U.S. APPLICATION This application is a continuation of application Ser. No. 159,838 filed July 6, 1971 now abandoned.

SUMMARY AND DETAILED DESCRIPTION This invention relates to apparatus for making molded pharmaceutical capsules by the dipping technique, that is, in each cycle by dipping a battery of mold pins into liquid solution and drying the resulting film coating on each pin to a hard shell suitable for a capsule part when cut to size. More particularly,the.invention relates to novel dipping apparatus.

Prior to the invention the industry has used forced circulation dipping pans of a standard type illustrated, for example, in U.S. Pat. No. 1,787,777. The conventional equipment includes a bath-like reservoir for the liquid dipping solution, a dipping pan nested within the reservoir, and a force-feed gear pump located in the base of the pan for cycling the dipping solution from the reservoir upward through open feed channels in the pan at a rate sufficient to keep the pan brimfull and overflowing. In this way, a constant liquid level is assured so that from one dipping cycle to another the depth of coating on each pin is maintained uniform. While this equipment has in the past been generally satisfactory from the standpoint of providing constancy of the dipping level, it nevertheless occasionally has failed to maintain uniformity in other standards set for the capsule, such as wall thickness standards. The problem has been attributed to improper mixing or distribution within the dipping pan. Efforts have been made to avoid turbulence in the dipping zone, forv example, using special equipment having individual shielding for 2 18a and 18b and extending lengthwise of the pan for driving off shaft 18a through coupling 19 by a suitable power source. The pan 11 is removably mounted in the reservoir by corner lugs (not shown) which, with each installation, serveto hold the pan in fixed position spaced on all sides from the reservoir walls 20 and bottom 21. For baffle purposes, the free space is comparteach pin (U.S. Pat. No. 2,975,477), but the problem largely remains, particularly where the mixing action at other areas in the apparatus fails to achieve complete uniformity or is delayed. 1

It is, therefore, an object of the present invention to provide means for achieving efficient capsule dipping at low cost using aqueous gelatin solution or other suit able dipping solution, while meeting existing product standards for high quality, uniform wall thickness, color, opacity, etc. v

This and other objects, advantages, and purposes of the invention will be seen in relation to the following description and accompanying drawings in which:

FIG. 1 is a top view of a capsule dipping pan and reservoir; I

FIG. 2 is a side view in section taken on line 2'2 of FIG. 1;

FIG. 3 is an end section taken on line 33 of FIG.

I; and I FIGS. '4, 5, and 6 are bottom views of preferred embodiments of a dipping pan mounted in a reservoir.

mented by corner walls 22 and side walls 23 and, according to preferred embodiments of FIGS. 4-6, the free space is compartmented into two halves by corner walls 22, side walls 23, and mid-wall 24. In a preferred form, the walls 22, 23, and 24 are unitary with the dipping pan and removable in one piece with the pan. The walls 22, 23, and 24 contact and closely fit with the inner surfaces of the reservoir; the walls also serve to center the assembly for mounting, as it is installed each time into the reservoir.

OPERATION In operation, the pan 11 is mounted in position as shown, dipping solution is introduced into the reservoir and pan, and the pump is activated to circulate solution upward through the pan and establish the liquid levels 120 and 12b. The course of flow through a vertical section is seen from FIG. 3: liquid at the dipping level 12a moves outward to edges A and B where it flows over and down along the outer walls of the sides 14a and l 4b and ends 15a and 15b of the pan to the reservoir level 12b. In the direction illustrated by dotted arrows, the liquid moves from level 12b downward to the reservoir bottom 21 at the mid-portion of which it enters a tunnel 25 bounded on four sides by the pan base 17, the reservoir bottom 21, and side walls 23.The liquid then traverses the-tunnel 25 and passes through apertures 26 into the pump and dipping pan 11 by way of channeling 27 in the floor 16 of the pan. The liquid completes the cycle by-spreading out and rising through the pan to level 12a. An important, element of the invention is the configuration which governs the horizontal flow pattern, particularly within the reservoir. Referring to FIG.

4-6 in this regard, the liquid descending to the reservoir in its cyclical flow must, according to the invention, move to either one or the other of the two ends The dipping apparatus, according to the invention, as.

shown in FIGS. 1 and 2, includes a reservoir' 1 0,and dipping pan 11 containing liquid dipping solution 12 maintained during operation at a constant dipping level 12a and also at a variable level 12b. Thereservoir 10 has a water jacket 13 for temperature control purposes.

The dipping pan, as seen in FIGS. 3 and 4, is rectangu 15a or 15b of the dipping pan. The route in turn depends onv which side of the comer walls 22 the liquid descends, .that is, whether from the .A or the B edges of the pan. In other words, the flow is divided, half of that overflowing at any given point. in time moves over the A edges and'half over the B edges. Significantly, the major part of the overflow, in its descent to the tunnel -opening, must traverse a substantial distance lengthwise of the reservoir in order to reach the ends-15a and 15b of the pan. This advantageously provides a highly efficient mixing action which is further enhanced-as. the liquid reverses direction and enters the tunnel 25. The action of thepump is such as to draw liquid'uniformly-throughthe apertures 26 so 'thatliquid present in the tunnel, confined as itis by theside walls 23 and. the optional mid-wall 24, is distributed evenly in itsflow to the apertures. When drawn into the pump, the liquid moves upward as. described. No special pumps'or added pumping capacityare, required. Also,

thedipping profile is flat, without crowning. For dipping, as illustrated in dotted outline in FIG. 3,, thecapsule pins 28 supported in rows from pin bars 29are lowered into the open pan. The quality of film formas tion obtained according .to the in vention has been found to be excellent. Also, temperature control and time required for mixing are significantly improved. For example, whereas the temperature gradient through the conventional dipping pan is from 1 to 2 C., the difference observed for the apparatus of the invention is commonly not more than 0.2 C. Also, where colored dyes or opaquing agents are added to the mix, the time required for complete mixing by conventional means is about 20 minutes whereas the instant apparatus requires only 5 minutes or less. The same advantage applies, in even less time according to the invention, for mixing fresh amounts of dipping solution required to be added from time to time to replenish losses in volume from ordinary operation.

The invention contemplates that conventional dipping equipment can be used for present purposes and that it can be modified at relatively low cost by adding the baffle wall means. This can be done in any suitable form. For example, the wall means can have the form of a unitary structure serving as a separate pedestal for supporting the pan 11 in the reservoir, or preferably it is permanently attached to the pan, that is, an integral unit with the pan. The wall means can be made of any material suitable for capsule dipping, preferably stainless steel sheeting of a non-pitting grade such as 316 stainless steel. A preferred thickness is about 0.125 inch. The wall means are preferably soldered to the pan and are soldered in sections using a high tin solder.

While the invention has been described in consider able detail in the specification, it will be realized by those skilled in the art that wide variation can be made in such detail within the spirit of the invention claimed below; it is intended that the claims be interpreted to cover both the invention, particularly described, and any such variation.

I claim:

1. In pharmaceutical capsule making apparatus including a bottom feed dipping pan adapted to contain a controllably overflowing fill of dipping solution and to receive in each dipping cycle a row of bar-mounted capsule mold pins for dipping each pin to a predetermined uniform depth,

the clipping pan being further adapted for mounting in spaced nesting relation within a bath reservoir containing dipping solution for supplying the pan with a continuing upward flow of dipping solution by way of aperture means centered along the length axis of the pan bottom,

the improvement comprising open-end tunnel means below the pan defined in part by the pan bottom and reservoir floor and in part by cooperating side walls coextensive with the side edges of the pan base, and upright wall means extending outward from two diagonally opposite corners of the pan and joining with the adjacent tunnel ends and reservoir wall and floor whereby overflow from opposite sides of the dipping pan is selectively channeled to opposite ends of the reservoir for lengthwise and depth-wise recycling to the dipping pan by way of the tunnel and aperture means.

2. Apparatus according to claim 1 wherein the tunnel is compartmented into two halves by mid-wall compartment means.

3. Apparatus according to claim 2 wherein the tunnel, wall, and compartment means are unitary with the dipping pan.

4. Apparatus according to claim 2 wherein the compartment means is a cross member joining the midpoints of the side walls.

5. Apparatus according to claim 2 wherein the compartment means is a member coextensive with the central length axis and with opposite halves of opposite ends of the tunnel means.

6. Apparatus according to claim 1 wherein the aperture means comprises a plurality of colinear open zones in the pan bottom, the zones being identical in shape, even in number, and equally spaced on the central length axis.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 {75 5759 Dated September -973 Inventor g Hugo JOSef Weyers It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Below "[21] Appl. No.: 310,829?" insert:

"[30] Foreign Application Priority Data 31, Belgiumoooooooooouo 92,342-.

Signed an d sealed this 9th day of April l97b (SEAL) Attest EDWARD M.FLETCHEB,JR. 0. MAR-SHALL DANN Attesting Officer Commissioner oi Patents FORM PO-IOSO (10 69) USCOMM DC eoiflbpog u.s covznnuzm' PRINTING ornc: Ian o-uhsu, 

1. In pharmaceutical capsule making apparatus including a bottom feed dipping pan adapted to contain a controllably overflowing fill of dipping solution and to receive in each dipping cycle a row of bar-mounted capsule mold pins for dipping each pin to a predetermined uniform depth, the dipping pan being further adapted for mounting in spaced nesting relation within a bath reservoir containing dipping solution for supplying the pan with a continuing upward flow of dipping solution by way of aperture means centered along the length axis of the pan bottom, the improvement comprising open-end tunnel means below the pan defined in part by the pan bottom and reservoir floor and in part by cooperating side walls coextensive with the side edges of the pan base, and upright wall means extending outward from two diagonally opposite corners of the pan and joining with the adjacent tunnel ends and reservoir wall and floor whereby overflow from opposite sides of the dipping pan is selectively channeled to opposite ends of the reservoir for lengthwise and depth-wise recycling to the dipping pan by way of the tunnel and aperture means.
 2. Apparatus according to claim 1 wherein the tunnel is compartmented into two halves by mid-wall compartment means.
 3. Apparatus according to claim 2 wherein the tunnel, wall, and compartment means are unitary with the dipping pan.
 4. Apparatus according to claim 2 wherein the compartment means is a cross member joining the mid-points of the side walls.
 5. Apparatus according to claim 2 wherein the compartment means is a member coextensive with the central length axis and with opposite halves of opposite ends of the tunnel means.
 6. Apparatus according to claim 1 wherein the aperture means comprises a plurality of colinear open zones in the pan bottom, the zones being identical in shape, even in number, and equally spaced on the central length axis. 